This invention relates to a process and an apparatus for the preparation of mixtures of isocyanate and water which are stable for a short time for glueing particulate material, in particular chips, fibers or the like, in which isocyanate is injected into the water at a high pressure.
The preparation of such mixtures for the above-mentioned purpose is difficult because isocyanate is immiscible with water except under certain conditions. The process of mixing must at present be carried out with high technical expenditure by the high pressure technique, using the counterflow injection method. Expensive high pressure pumps are required for dosing the two components. Mixing takes place in a counterflow injection mixing head at pressures from about 100 to 300 bar and the mixture is subsequently applied to the chips either by means of airless spray nozzles or pressure-free, with or without the assistance of air. Part of the energy expended is thus utilized for atomizing the mixture but the expenditure in apparatus is nevertheless very high. Due to the high level of energy employed, the apparatus is subject to severe stress and wear, and considerable servicing and maintenance is required in particular for the parts of the apparatus which carry water.
It is an object of the present invention to develop a simple process and inexpensive, trouble-free apparatus for preparing a mixture of isocyanate and water which is stable for a short time.